Mercury Racing, in conjunction with the American Power Boat Association (APBA), has announced that the APBA Factory Stock offshore racing class will adopt the Mercury Racing 500R outboard as specified power, commencing with the 2025 racing season. The Mercury Racing 500R will replace the discontinued Mercury Racing 450R outboard in this class, and the class name will change from Factory Stock 450 to Factory Stock 500.

“We’ve been talking to the race teams about making this change for more than a year, and I think everyone is excited about stepping up to Mercury Racing 500R outboards for 2025,” said Jeff Broman, Director, Mercury Racing. “Every racer craves more power, and the teams want to race with the product that’s currently available to the public. The 500R offers racers the latest advancements from Mercury Racing, including humidity compensation technology for consistent performance in the broad range of atmospheric conditions teams encounter in a season, from the Florida coast to the Great Lakes.”

The Mercury Racing 500R delivers 50 more horsepower plus 10% more torque than the 450R model it replaces in the Factory Stock class. Its 4.6-liter 64-degree DOHC V8 powerhead is boosted by an exclusive Mercury Racing supercharger. Weighing as little as 720 pounds, the 500R establishes a new benchmark for outboard power density. The Mercury Racing 500R features exclusive components and features to optimize its performance potential, including the R-Drive and R-Drive Sport gearcases, the Advanced Racing Core (ARC) midsection, and upgraded engine and cooling system designs. This allows the engine ECM to maintain the most aggressive calibration possible to optimize performance under virtually all conditions. The result is a significant gain in power in challenging, very humid conditions—up to 30 additional horsepower than would be available without humidity compensation.

The 500R outboards prepared by Mercury Racing for Factory Stock competition will feature the following changes from regular production specifications:

• A revised ECU calibration permits higher peak RPM for broader propping options, and a less-aggressive Engine Guardian program.
• Standard engine mounts are replaced with heavy-duty mounts for enhanced stability and durability under the most extreme conditions.
• The cooling system is modified to be compatible with high transom mounting positions by removing the idle relief muffler, which permits higher exhaust temperature.
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For competition, the 500R outboard will be offered two gearcase options. Racers may choose the production R-Drive Sport 5.9-inch surfacing gearcase with a 1.5-inch diameter propshaft. Teams with a significant investment in racing propellers for the 450R outboard may select the race-proven Speed Master gearcase with a 1.25-inch diameter propshaft and continue to use those propellers. Mercury Racing will offer a full range of five-blade CNC Cleaver propellers for both the R-Drive Sport and Sport master gearcase.

“The transition to 500R power should be seamless,” said Broman. “Teams should not have to make significant changes to boat rigging or weight distribution. The consumer versions of these boats are already running the 500R production outboard, and the builders have the set-up dialed in. We expect that Factory Stock boats powered by the 500R outboard will see up to a 5 mph gain in potential top speed compared to 450R outboard power.”

The Factory Stock 500 class is designed to foster close competition and features 35-foot to 40-foot catamaran boats equipped with full safety canopies, including models produced by Marine Technologies Incorporated (MTI), Doug Wright Powerboats and Skater Powerboats. Each is powered by twin Mercury Racing 500R outboards. All boats must be out of a production mold as certified by Offshore Powerboats Association (OPA) Racing. No custom-built boats are permitted and the outboard engines are stock and factory sealed. The Factory Stock class competes on a closed course that is typically five miles in length with multiple turns. The boats are capable of a top speed exceeding 130 mph on flat water but are usually propped shorter for improved acceleration.

Learn about the Mercury Racing Wide Open lifestyle and all Mercury Racing high-performance products at Mercuryracing.com.

Based in Fond du Lac, Wis., Mercury Racing, a division of Mercury Marine, is a leading provider of high-performance marine propulsion systems for discriminating boaters worldwide, offering an exciting and fulfilling power boating experience on the water. Using leading-edge technology, Mercury Racing produces high-performance outboards, sterndrives, propellers, parts and accessories. Mercury Marine is a division of Brunswick Corp. (NYSE: BC), the world’s largest manufacturer of pleasure boats, marine engines, and accessories.

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